Would you like to learn to predict the weather? One way to do that is to use a barometer to measure atmospheric pressure—in other words, how heavy the air is. Low pressure tells us that clouds and rain are probably on the way, while high pressure days tend to be clear and often sunny. It’s easy to make your own barometer from materials you probably already have at home.
- Deflated balloon
- Wide-mouth glass jar (no lid)
- Rubber band 2 plastic drinking straws
- Clear tape
- Cardstock or poster board
- Pencil or marker
What to Do:
1. Make a careful, straight cut across the balloon (about halfway down) to remove the neck.
2. Stretch the rest of the balloon tightly over the top of the jar and hold it fast by stretching the rubber band around the neck of the jar.
3. Trim the straw to about 6 or 7 inches long. Cut each end of the straw on an angle, so the ends are pointed.
4. Tape one end of the straw to the center of the balloon stretched over the jar top. If the tape isn’t strong enough, add a dab of adhesive.
6. Use the ruler to draw a line in the center of the cardstock or poster board. Write “High Pressure” at the top and “Low Pressure” at the bottom.
7. Fold the right 1/3 and left 1/3 of the cardstock or poster board backward to form a triangle, so the chart can stand alone.
Bring your barometer outside and set it up so that the pointer straw is lined up with the chart. Watch what happens to the atmospheric pressure on a sunny day, then on a cloudy or rainy day. After a few days, bring your barometer inside and place it on a shelf or table. Continue to check the pressure each day. How do your readings match what’s happening outside? Keep track of your measurements in a notebook so you can get even better at predicting the weather. For more activities and info on weather forecasting, download Weather: What Do You Know?